The present invention concerns a device for lighting the passenger compartment of a motor vehicle.
In the automotive world, manufacturers seek both technical innovations aimed at improving vehicle performance and safety and also technical innovations producing esthetic effects to improve the onboard ambience or style of the vehicle.
Thus there exist lighting devices the effect of which is to set up a particular ambience in the passenger compartment of the vehicle thanks to the intensity or the color of the lighting. Also, some lighting devices provide information on parameters of the vehicle, for example on the dashboard.
For example, in the case of heating and/or air-conditioning systems, there may be a requirement to give an indication of the temperature by means of luminous signals having a specific color. Actually, a display may be used to show the ambient temperature in the passenger compartment, the temperature figure being a certain color when the temperature is high and a different color when the temperature is low.
The document US2007/0046452 describes an improved lighting device that is disposed in a ventilation duct of a heating and/or air-conditioning system, the duct including an opening leading into the passenger compartment of the vehicle, so that the beam is visible to the occupants of the vehicle. This device diffuses light of one specific color, for example red, when the temperature of the duct is above a threshold value and another specific color, for example blue, when the temperature of the duct falls below another threshold value.
However, this device is limited to two colors and two temperature threshold values. The visual perception of temperature given by the lighting device is therefore imprecise. Actually, the temperature value is deduced only at the time of one of the two colors changing or being turned on. If the temperature continues to rise or to fall, the corresponding lighting color remains the same.